Thermostatic compensating device for fluid meters



.A'. J. GRANBERG Jan. 5, 1937..

THERMOSTATIC COMPENSATING DEVICE FOR FLUID METERS Filed Aug. 2, 1953 }1NVENTOR. Y B *6- 4 I I ATTORN YS.

Patented Jan. 51937 PATENT OFFICE THERMOSTAHQ COMPENSATING DEVICE- FOR FLUID METERS Albert J. Graiilierg, iier eley. can. 7 Application August 2, 1933;, Serial No. 683E316? 3 Claims. (OLE-71239} This invention relates to fluid meters and more particularly to-iinp'rovements in meters of the type disclosed in my prior Patent 1,811.789101 Fluid meter issued June 23, 1931. The im- 6 provements are in the nature of means for compensating for changes in volume of the fluid being metered caused by temperature variations.

It is the object of the present invention to provide an improved meter which comprises means .W'a'ctuated by variations in the temperature of the-fluid being metered to compensate for volume changes causedby said tem erature variations end to provide ameter' which said compensat ing means" are simple in construction, accurate operation. and capable of adjustment for use with various types of fluids. object is obtained by the combination of, a'a m'eter ofthe positive displacement type and of means associated with one of the pistons of 20" the meter for injecting a predetermined volume of liquid into the discharge line of the meter up'or'i thedischai e stroke of the piston. m "s" consists of anauxiliary piston connected wit the main piston' of the meter for recipro= caltion therewith. Means are provided- -for vary; ing the stroke' of the auxiliary piston so that the volume of-iluid injected by it into the dis-' charge line'will be .changed-,- and this means is; actuated by a thermosensitivedevice immersed 810 the fluid being metered.

One" form of my invention is exemplified'in-theaccompanying drawing and described in the fol-* lowing specification which further of its-10bjectsbandadvantages are made apparent.

' In' th'edr'awing I Fig. 1 is a view partly in vertical longitudinal. section ofa meterembodying myinvention. and is" taken on the lineI- Iof Fig.2; I

' Fig.2 "is an end view ofthe same meter-with portion th'ereof shownsinsectionon-the line 11-";11 of Figt liand Fig. 3 is a fragmentary sectional-,view taken on the 1ineIII-III1Qf Fig. 2. u"

Referring-more particularly to the .drawing, -I .showuwmeter' casing H1;- at one end of which is an inlet port II and at .the opposite end a dis chargeportals-2. Within the casing I are a pair of pistons mountedfor; reciprocal and oscil: leit'ors :movement; 1 orient-which is shown a-t i 3. 'I he iii'd'to'be'meteredzis delivered to'the.interior otithesmeterthousing .atroppositeends: ofthe pistonscthrough ports thecylinder- .walls; surrounding the pistons;v which are opened and closed @133 ireciprocal" and oscillatory movement fifi'fli :pistoriszinz-a manner to eiiect-metering of the fluid. Each of the pistons is provided with a crank pin such as is indicated at [9, which rotates a crank I5 andpthe motion of this crank is transmitted through suitable mechanism not shown to operate a counting and totalizing device situated within the casing l6 surmounting the meter casing in. As all of thestructure above referred to is disclosed my above mentioned patent, further detaileddescription of the same will be unnecessary for an understanding of the present invention.

Qne end of the meter casing ID is provided wit op n n adj ce t the dischar e p l2, and a housing I! is fitted over this opening and-[secured in place by means of bolts, as indicated at 18., A cover plate [9 is secured to h h m ng H b screws 19- A the housing is fitted .over n; opening adjacent one end of the piston I 3,- 1;t i s obvious that its interior will be filled with fluid which enters the meter through the inta lg e i Formed within -thehousing fl isa small au-giiliary' cylinder' 2 l iorthe reception of an aura ar p ton- 22which' is reciprocally he 11 nd provided with a stem 23 am s; P 8 5 dini cover p ate m ter is in operation, fluid enter V Z take His directed first to one end of the v H .l-3 to urge it in one direction and th ce to theotherend to urge it in the oppositedireetioni Each phase of tliisreciprocalnlovement of the Piston serves to e'zipel the re rrg h the end n61 much it was last directed throughs a ports [and finally out through the dischargepo -l2.

Uponeachstroke of the piston I 3 toward the closed of the auxiliary cylinder fl, it incidentall'y glimps small amo nt of fluid n-em thei cylind efi" .21 into the discharge line. The n ger 2| cornm ates with the discharge line through a; cat e closed end of the cylinder 2l wh1 "port is lustrated in Fig 2 where the piston 22 sh ens broken away to disclose the p "e. The volume .of fluid thus injectedin o t' e di halge'lineby the' piston 22 is not taken. into -c 'sjideratioh' in computing the normal disp cement of the meter because the" fluid- 50 ju 'ea wee withdrawn from the discharge of the meter and consequently the reading of the counting mechanism will be accurate. The means vfor reciprocating the piston 22 areas follows;

A lever; 26" pivotedto' a pin'lll supported in a bracket 28 ea cover'lplate l9 extends upwardly through a hole reformed in the stem 23 of the piston. Aconn'ectingfrod 30 is slidably received by a hole 3| in the upper end of the lever 26 and connected at one end by means of a universal connection 32 with the piston I3. The opposite end of the connecting rod 30 is fitted with a collar 33 held in a position of adjustment longitudinally of the connecting rod 30 by means of lock nuts 34. A spring 35 normally urges the lever 26 to withdraw the piston 22 and movement of the main piston l3 in the direction of the arrow a causes the collar 33 to engage the lever 26 and move the piston 22 into its cylinder. Therefore, when the main piston is reciprocating,

the auxiliary piston 22 reciprocates synchronously, being pulled in by means of the connecting rod 30 and pulled out under the tension of the spring 35. As long as the temperature of the fluid being metered remains constant, the volume of fluid injected by the auxiliary piston into the discharge line upon each stroke remains the same. When the temperature of the fluid changes, means are provided for varying the stroke of the auxiliary piston 22 and thereby changing the volume injected by it into the discharge line so as to compensate for the change of temperature.

The stroke of the piston 22 is changed by means of a cam 36 which is disposed in a position obstructing the swinging movement of the lever 26. The cam 35, which is of a generally spiral shape, is fixed to a shaft 31 journaled in the brackets 28 so that upon rotation of the shaft 31 the point on the cam which engages the lever will be advanced or retracted to determine the distance of withdrawal of the piston 22 under the tension of the spring 35. One end of the cam shaft 31 is fitted with a gear 39, and this gear meshes with a segmental rack 40 carried at the end of a lever 4| which is pivoted on a pin 42 fixedly supported in a bracket 43 formed on the cover plate l9.

Fixed to the pin 42 on opposite sides of the lever 4| are a pair of thermosensitive elements 44. These elements, which may be in the form of the conventional bi-metallic strips manufactured for this purpose, are secured at one end to the shaft 42 curved about the shaft in a helical path and terminate at their opposite ends between a pair of pins 45, which pins secure them with relation to the lever 4|. The interior of the housing IT, as before stated, is filled with the fluid being metered, and the thermosensitive elements 44 are therefore immersed in said fluid and assume its temperature. Consequently, upon variations in temperature of the fluid, the elements 44 expand'and contract and in so doing their outer ends swing the lever 4| about its pivot 42 with the result that the rack 40 rotates the gear 39 to change the position of the cam 36. The thermosensitive elements 44 are resilient and they are preferably arranged at slightly different degrees of tension to eliminate lost motion which would otherwise be possible upon movement of the lever 4| in opposite directions.

In order to adjust the meter for use with fluids having different coeiiicients of expansion, the effective length of the connecting rod 30 may be changed by adjustment of the position of the nuts 34.

In the operation of the device, the meter, as above described, is connected with a source of fluid supply to receive fluid therefrom through the intake The fluid reciprocates the meter pistons and the reciprocation of the pistons'discharges the fluid in measured quantities through the discharge port l2. In order to understand the operation of the auxiliary piston 22, it must be pointed out that when the main piston |3 moves in the direction of the arrow a, it is on its intake stroke so that fluid will flow into the metering chamber at the left-hand end of the piston l3, Fig. 1, from the inlet of the meter, seeking to fill this chamber. Toward the end of the intake stroke of the piston [3 in the direction of the arrow (1, the collar 33 on the connecting rod 30 engages the lever 26 to move the auxiliary piston 22 in the direction of the arrow a, Fig. 1, thus enlarging the metering chamber. The port 25 enables any fluid between the auxiliary piston 22 and the end of the auxiliary cylinder 2| to be discharged into the discharge line of the meter.

Assuming now that the piston l3 has travelled the full distance of its intake stroke in the direction of the arrow a, Fig. 1, and that the connecting rod 30 through the medium of the collar 33 has moved the lever 26 forwardly to advance the auxiliary piston 22 in the auxiliary cylinder 2|, when the piston l3 commences moving in the opposite direction, or in its discharge stroke, the piston 2.2 will likewise be urged in this direction by the spring 35. Thus, the volume of fluid discharged from the metering chamber will be the combined displacement of the main piston I3 and the auxiliary piston 22.

It is immaterial whether or not fluid is drawn from the discharge line by the suction of the auxiliary piston 22 through the port 25, because this amount drawn in will be subsequently discharged back into the discharge line so that there will be no inaccuracy. However, due to the fact that the displacement stroke of the auxiliary piston 22 is automatically varied by the temperature of the liquid being metered, the combined displacement of the main piston l3 and the auxiliary piston 22 will be varied to compensate for temperature changes.

It is seen that the spring 35 is the medium which moves the, piston to the left, Fig. l, on its displacement stroke, and this displacement stroke is not limited in any manner by the action of the piston I3, but is limited by the position of the cam 36, the position of which cam is controlled by the thermosensitive elements 44 through the lever 4| and the gear 39. Thus, the combined displacements of the pistons l3 and 22 is directly proportional to the temperature of the fluid being metered, and the accuracy of the meter is unaffected by variations in temperature. The stem 23 and the bearing 24 act as a sort of a dashpot medium to control the retraction of the piston 22.

From the foregoing it is apparent that I have provided a novel device which, through simple mechanical means, accurately compensates for differences in temperature of fluid passing through a meter of positive displacement type.

While I have shown a preferred form of my invention, it will be understood that various changes may be made in the construction and arrangement of its several parts within the scope of the appended claims.

Having thus described my invention, what I claim and desire to secure by Letters Patent is:

1. In combination with a fluid meter comprising a reciprocable metering piston and adapted to be connected with a supply line and a discharge line, a chamber adjacent the meter and in communication with the meter, a cylinder in said chamber communicating with the discharge line, an auxiliary piston in said cylinder resilient means normally holding the auxiliary piston withdrawn, means connecting the auxiliary piston with the metering piston whereby the aux iliary piston will be advanced upon each reciprocal stroke of the metering piston to inject fluid into the discharge line, and. temperature responsive means for varying the stroke of the auxiliary piston to compensate for variations in temperature of the fluid.

2. In combination with a fluid meter comprising a reciprocable piston and adapted to be connected with a supply line and a discharge line, a chamber adjacent the meter and adapted to be in communication with the meter, a cylinder in said chamber communicating with the discharge line, an auxiliary piston in said cylinder, a spring pressed lever pivoted within said chamber and connected with said auxiliary piston to normally urge it to a withdrawn position, a connecting rod carried by the metering piston and slidably extending through said lever, a collar on said rod to engage the lever and advance the auxiliary piston upon movement of the metering piston in one direction to cause the auxiliary piston to inject a quantity of fluid into the discharge line, a cam engaging said lever to limit the withdrawal of the auxiliary piston and thereby control the quantity of fluid injected into the discharge line by it, and a thermosensitive element immersed in the fluid in said chamber to vary the position of said cam upon variations in temperature of the fluid.

3. In combination with a fluid meter comprising a reciprocable piston and adapted to be connected with a supply line and a discharge line, a chamber adjacent the meter and adapted to be in communication with the meter, a cylinder in said chamber communicating with the discharge line, an auxiliary piston in said cylinder, a spring pressed lever pivoted within said chamber and connected with said auxiliary piston to normally urge it to a withdrawn position, a connecting, rod carried by the metering piston and slidably extending through said lever, a collar on said rod to engage the lever and advance the auxiliary piston upon movement of the metering piston in one direction to cause the auxiliary piston to inject a quantity of fluid into the discharge line, a cam engaging said lever to limit the withdrawal of the auxiliary piston and thereby control the quantity of fluid injected into the discharge line by it, and a thermosensitive element immersed in the fluid in said chamber to vary the'position of said cam upon variations in temperature of the fluid, and means permitting adjustment of the position of said collar on said connecting rod to adapt the device to various types of fluid.

ALBERT J. GRANBERG. 

